Drug interactions
Fentanyl transmucosal + Promethazine
Severity: Major
Fentanyl transmucosal and Promethazine: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Promethazine is a sedating phenothiazine antihistamine, and transmucosal fentanyl is a rapid-onset potent opioid. Concurrent use raises the risk of profound sedation, respiratory depression, hypotension and coma. Opioid labeling warns about concomitant CNS depressants.
What this interaction means in plain words
Fentanyl transmucosal and Promethazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive central nervous system and respiratory depression from opioid agonism combined with sedating antihistamine and phenothiazine effects.
What to do
Use together only when alternatives are inadequate, with the lowest effective doses and shortest duration. Monitor closely for sedation and respiratory depression.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Fentanyl transmucosal with Promethazine?
MediHelp rates the interaction as major. Fentanyl transmucosal and Promethazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Promethazine is a sedating phenothiazine antihistamine, and transmucosal fentanyl is a rapid-onset potent opioid. Concurrent use raises the risk of profound sedation, respiratory depression, hypotension and coma. Opioid labeling warns about concomitant CNS depressants.
How serious is the interaction between Fentanyl transmucosal and Promethazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use together only when alternatives are inadequate, with the lowest effective doses and shortest duration. Monitor closely for sedation and respiratory depression.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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